Development of microstructure and evolution of rheological characteristics of a highly concentrated emulsion during emulsification

The refining characteristics of the highly concentrated water-in-oil emulsion, which are used as ‘emulsion precursors’ for the preparation of emulsion explosives, were investigated to elucidate the manner in which the refining time influences its microstructure and rheological behaviour. The development of microstructure at various stages of the emulsification process has been studied in detail and an empirical correlation between the characteristic droplet size and refining time has been proposed. The evolution of rheological characteristics of the emulsion during the microstructure refinement has been investigated through different protocols of the dynamic and steady-state rheology. An extended refining led to a finer microstructure and resulted in an increase in the elastic modulus, yield stress and viscosity of the emulsion. The droplet size dependency of the elasticity and the yield stress during the refining have also been discussed. The network structure of the dispersed phase, the droplet size and the corresponding interdroplet interactions all govern the rheological characteristics of the final emulsion.